The present invention relates to a light-receiving unit, and a method and device for digital image input for converting analog data generated by a light-receiving element to digital data and inputting the digital data as image data. The invention relates more specifically to a light-receiving unit, a method and device for digital image input for determining whether image data is to be generated or not according to a change rate of analog data (voltage value) generated by converting the light into an electricity signal with a light-receiving element according to amplitude of the received light.
In a digital image input device based on the conventional technology such as a CCD camera, a plurality of CCD (a solid image pick-up element or a light-receiving element) each capable of converting received light to electricity according to amplitude of the received light are arranged in a matrix form. Voltage values (analog data) generated by each CCD are acquired by successively scanning at a specified sampling cycle and the values are converted to digital data and inputted as image data.
In this way, image data inputted at each scan is an image data corresponding to each of the CCDs arrayed in a matrix form. In other words, assuming that all the CCDs arrayed in a matrix form a screen, image data for one screen is inputted by scanning once. For instance, when a digital image input device is a digital camera, image data for one screen inputted at one scan is equivalent to a sheet of still image. When a digital image input device is a video camera, image data for several tens of screens per unit time (namely, a dynamic picture) is acquired by scanning several tens of times per unit time.
However, image data for one screen is generated and inputted unconditionally according to analog data (voltage values) obtained by scanning with CCDs arrayed in a matrix form at a specified sampling cycle, so that there occur the problems as described below.
Main object of photography or shooting is to record changes in the state of an object or a space. However, with the scan line system based on the conventional technology, even when there is no change in the state of the object or the space, image data is generated and inputted by unconditional scanning the state of the object or the space at a specified sampling cycle. Thus, when there is no change in the state of an object or space, image data is unnecessarily generated and inputted. Especially, when a state of an object or a space changes little but the photography or shooting is executed for a long period, a quantity of image data disadvantageously becomes large.
Any screen comprising CCDs arrayed in a matrix form is taken as a unit for input of image data, and even when only a particular portion of image data for one screen changes, image data for one screen is generated and inputted. Thus, in the image data for one screen, a lot of unnecessary image data having no special information is generated and inputted.
Thirdly, in the conventional technology, a sampling cycle (in other words, a time interval at which the image data is generated and inputted) for acquiring analog data (voltage values) from each CCD is restricted by preset requirements. For instance, in a case of sampling cycle at which image data for 60 screens (frames) is inputted per second, a time interval between image data of one screen and its privious or next screen is {fraction (1/60)} second. When the image data inputted at this rate is reproduced slowly, screens acquired at a time interval corresponding to a sampling cycle are reproduced with a timely extended interval, so that the reproduced images look like thinned ones and a smoothness in the movements is lost. When the sampling cycle is made shorter, the smoothness in slow reproduction can be improved, however, in this quantity of image data increases.
It is an object of the present invention to enable generation and input of the image data corresponding only to changes in the state of an object or a space.
It is another object of the present invention to enable input of image data corresponding to the changes in state with each light-receiving unit such as a CCD for the purpose to evade generation and input of unnecessary image data not including change in state (unnecessary information) to reduce a quantity of data to be processed and improve efficiency in input of image data.
It is another object of the present invention to suppress increase of image data and improve smoothness in reproduction even at a low speed.
Other objects and features of this invention will become clear from the following description with reference to the accompanying drawings.
In the light-receiving element unit according to the present invention, an A/D converting unit converts analog data of each light-receiving element into digital data, a storage unit stores a reference data, a determining unit decides that the digital data to be used for generation of the image data when an absolute value of a difference between the digital data and the reference data is equal to or more than a preset threshold value, an image data generating unit generates the image data, and a reference data updating unit updates the reference data, so that image data is generated only when there is a change of state of the object or the space and unnecessary data is not generated.
In the digital image input device according to the present invention, an A/D converting unit converts the analog data from the plurality of light-receiving elements into digital data, a storage unit stores a reference data, a determining unit decides that the digital data to be used for generation of the image data when an absolute value of a difference between the digital data and the reference data is equal to or more than a preset threshold value a first image data generating unit appends a specific address data and a time code for identification of the image data, a reference data updating unit updates the reference data, so that image data is generated only when there is a change of state of the object or the space and unnecessary data is not generated.
In the digital image input method according to the present invention, a change rate of a voltage value generated in a light-receiving element is accumulated, and when the accumulated value of change rate is out of a preset range, image data is generated and inputted by using the voltage value at the point of time, so that image data is generated only when there is a change of state of the object or the space and unnecessary data is not generated.
In the digital image input method according to the present invention, a voltage value sampled last with a prespecified sampling cycle is compared to a previous voltage value used for generating the previous image data for each light-receiving element, and when an absolute value of a difference between the previous voltage value and the current voltage value is equal to or larger than a preset threshold value, the previous voltage value is updated to the current voltage value, and image data is generated and inputted by using the current voltage value, so that image data is generated only when there is a change of state of the object or the space and unnecessary data is not generated.
In the digital image input method according to the present invention, light is received in a light-receiving section having a plurality of light-receiving elements, a voltage value is obtained based on the amplitude of the light, a difference is obtained between the voltage value and a reference value, the voltage value is used for generation of image data when absolute value of the difference is larger than a preset threshold value, a first image data is generated using the voltage value, a specific address data and time code is appended to the first image data, and the reference data is updated using the using the voltage value, so that image data is generated only when there is a change of state of the object or the space and unnecessary data is not generated.